Displacement Tracking System Based On Machine Vision Research And Application

Structural displacement is one of the most important physical quantities contained in structural health monitoring (SHM). Measurement of structural displacement of large-scale civil engineering structures such as long-span bridges, super-tall building, has always been a challenging task. Various traditional contact-type sensors have been implemented for monitoring structural displacement but have some limitations.In order to overcome these problems described above, in recent years, some methodologies based on vision technique for structural health monitoring has raised attention increasingly. However, the existing methodologies as reviewed above suffer from several problems.In this study, a vision inspection system comprising an industry camera, an optical lens and vision-based localization software has been developed for monitoring of structural dynamic displacement in real-time, remote and non-contact manner. In addition, a more robust software based on machine vision algorithm which is used for target localization was developed and implemented through the LabVIEW graphical programming language.Finally, four different experiments, including depth testing of plastic card with dial gauge, the displacement response measurement of mass and testing mode on shaking table, the vertical deflection monitoring of mid-span of StoneCutters Bridge and the displacement monitoring of sharp rail of railroad switch, were conducted in the laboratory or on the field to verify the measurement accuracy and feasibility of this system. All testing results demonstrate that the vision-based inspection system can be utilized for monitoring the dynamic displacement of structure successfully.